Punctate epithelial erosions are associated with the following: viral keratitis, especially molluscum contagiosum; inclusion conjunctivitis; herpetic keratitis/postinfectious herpetic keratitis; rubeola and rubella; keratitis sicca; exposure keratitis; vernal conjunctivitis; topical steroids; and vaccinia.
Other conditions associated with recurrent corneal erosions include the following: Thygeson superficial punctate keratitis, herpes zoster, adenovirus infections, prolonged eye patching, corneal edema, keratoconus, neuropathic keratopathy, degenerative condition of the cornea (eg, advanced glaucoma), aerosol keratitis, ectodermal dysplasia, acne rosacea, postcataract surgery, and trauma (eg, wounds, abrasions, exposure to short-wave diathermy).
Epithelial basement membrane dystrophy (map-dot-fingerprint dystrophy): Epithelial basement membrane dystrophy is the most common corneal dystrophy, affecting approximately 2% of the population. Although most patients remain asymptomatic, about 10% experience recurrent corneal erosions as a consequence of faulty attachment complexes. These attachment complexes consist of hemidesmosomes of the basal epithelial cells, the underlying basement membrane, and the subadjacent anchoring fibrils of the Bowman layer.
Diabetes mellitus: Corneal opacities, dry eyes, and changes in the Descemet membrane have rarely been observed in patients with diabetes. It has become apparent that patients with diabetes have a problem related to epithelial adherence to the Bowman layer. Significant recurrent corneal erosions have been reported after intraocular surgery and specifically after vitrectomy on such patients.
In the nondiabetic cornea, corneal epithelial scraping results in rupture of the basal cells with maintenance of the basement membrane attachment to the Bowman layer. However, in the diabetic cornea, the entire epithelium separates as an intact sheet with the entire basement membrane remaining adherent to the basal cells. Use of prolonged semipressure patching and bandage soft contact lenses is recommended in the event that such corneal changes occur after intraocular surgery.
Cystinosis: The clinical feature common to the 3 types of cystinosis is the pathognomonic deposition of cystine crystals in the cornea and conjunctiva. Severe photophobia is often the only presenting visual symptom. The symptoms result from the diffraction of light by the corneal crystals. The fusiform crystals initially involve the anterior portion of the central cornea but occupy the full thickness of the peripheral cornea by age 1 year. No visual impairment occurs in the early stages.
By age 7 years, most patients have crystals either within or on the endothelial surface of the cornea, with markedly decreased corneal sensitivity. Decreased tearing and painful corneal erosions occur. Corneal thickness is increased. The conjunctiva has a ground-glass appearance. Birefringent, hexagonal, polychromatic, polymorphic, rectangular, or rhomboidal crystals can be seen with the biomicroscope.
Toxic epidermal necrolysis/Stevens-Johnson syndrome/erythema multiforme: Toxic epidermal necrolysis (Lyell disease, Ritter disease, scalded skin syndrome) is an acute systemic illness associated with a bullous eruption of the skin and mucous membranes that, in many respects, is similar to Stevens-Johnson syndrome.
Ocular involvement in toxic epidermal necrolysis is limited to the conjunctiva; it is usually less severe than is the ocular involvement in Stevens-Johnson syndrome. A mucopurulent conjunctivitis is the most common early manifestation, and, unlike the involvement in erythema multiforme, this does not usually result in ulceration, scarring, symblepharon, or corneal pannus formation. However, it may do so, with recurrent corneal erosions and all the other consequences described for Stevens-Johnson syndrome.
Trachoma: The constant corneal abrasion by the lashes and inadequate tears can produce corneal erosions, ulceration, and opacity, which constitute the major pathway to blindness in trachoma. In this case, there is notching of the upper lid due to previous lid surgery; this can produce corneal exposure and further corneal damage.
Corneal epithelium changes eventually occur in all patients with aniridia. A superficial, slightly elevated, faint gray pannus with fine radially oriented blood vessels that stain positive with fluorescein is characteristic. Defects appear in the corneal periphery and progress to the center with age.
In some cases, corneal erosions and frank ulceration occur whether or not glaucoma is present. These lesions may progress to end-stage corneal scarring involving all layers. Others have described avascular opacities present at birth, involving the Descemet membrane and the deep stroma. Technically, these corneal opacifications cannot be considered dystrophies. Microcornea is a frequent finding.
Mucolipidosis IV: Mucolipidosis IV, also referred to as Berman syndrome, is a rare storage disease characterized by severe psychomotor retardation and early corneal clouding. It differs from mucolipidosis I, II, and III in its lack of skeletal abnormalities. Patients show developmental delay and progressive psychomotor deterioration. Survival is variable. Corneal clouding may be present at birth, or it may develop later. The clouding is primarily due to epithelial involvement. Marked corneal surface irregularities may be present. Some patients experience bouts of pain, tearing, photophobia, and conjunctival injection, possibly related to recurrent corneal erosions. Lubrication may be helpful.
Lattice dystrophy type II (Meretoja syndrome): Lattice dystrophy type II is found in familial systemic amyloidosis (Meretoja syndrome, type IV familial neuropathic syndrome). This also is an autosomal dominant disease, usually found in patients of Finnish, Dutch, or Scotch-Irish ancestry. Systemic involvement consists of progressive cranial and peripheral neuropathies, skin changes, and multisystemic involvement secondary to eventual deposition of amyloid throughout the body. The corneal changes usually are quite mild, presenting in the third decade or later. Recurrent corneal erosions and poor vision can occur. In contrast to lattice dystrophy type I, the refractile lines are located peripherally, are fewer in number, and are larger.
Filamentary keratitis: Combination of punctate epithelial keratitis and increased mucus are the necessary ingredients for filamentary keratitis. In filamentary keratitis, important differentiating features for the numerous causes include the location of filaments, tear film status, and the presence of associated ocular disease.
Filamentary keratitis occurs with numerous disorders other than keratoconjunctivitis sicca (KCS) and superior limbic keratoconjunctivitis (SLK). Recurrent erosion, postcataract extraction, postpenetrating keratoplasty, neurotrophic keratitis, herpetic keratitis, bullous keratopathy, prolonged patching (padding), and hereditary hemorrhagic telangiectasia are among these disorders.
Whatever the cause, filament formation results from a derangement in the corneal epithelium and a relative excess of mucus. The excess mucus usually is secondary to chronic irritation, and the location of the filaments depends on the type of underlying corneal pathology. Herpes zoster ophthalmicus produces changes in the corneal epithelium, probably as a consequence of denervation and alteration in tear secretion.
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